1. Field of the Invention
This invention relates generally to a brake, shear and cable management system and method, and in particular to a brake, shear and cable management system attachable adjacent to a rotatable drum and having a cable management assembly, a cable brake assembly and a cable cutting assembly used in conjunction to manage, retain and sever a spent portion of cable upon the drum.
2. Description of the Related Art
The major components of a drilling rig hoisting system consists of a mast or derrick, a crown block, a traveling block, wire rope and a drawworks. The drawworks is used to lift or lower the drill pipe assembly into or out of the hole being drilled. The drawworks is essentially a large winch, having a drum to spool (wrap) or unwrap wire rope for the purpose of lifting or lowering the drill pipe assembly. Thus, the drum is able to rotate in either direction and is controlled and powered by a drive motor.
The wire rope is supplied to the drilling site on a large spool and is typically 0.5-to-2 inches in diameter. Initially, in setting-up the drilling rig, the wire rope is pulled from the supply reel through the deadline anchor and then sequentially threaded through the sheaves in the crown block and traveling block to achieve the number of lines required to support the drilling assembly planned for the wellbore. When the wire rope end has been strung over the final crown block sheave, this wire rope end is pulled down to the drawworks drum at the rig floor where it is threaded into the dogknot hole and clamped. Then the drum is rotated to pull the wire rope through this system of sheaves in order to wind-up several layers of wire rope onto the drum. The wire rope is unspooled from the supply reel. Finally, the deadline anchor is tightened, which holds the wire rope fixed at that end and then the traveling block can be raised or lowered by the rotation of the drawworks drum. The wire rope is never cut between the supply reel and the deadline anchor.
During the drilling of the wellbore, the traveling block moves up and down many times while lifting large loads (can be 250-tons or more). The wire rope bends around the sheaves and is spooled onto the drum under load many times, which causes wear. The rig crew monitors this wear using an instrument that tracks the ton-miles of use for this section of wire rope from the supply reel. When a threshold number of ton-miles has been reached (set by their cut-and-slip program for wire rope maintenance), the used section of wire rope must be retired from service.
To perform the wire rope cut and slip, the traveling block is suspended by a “hang-line” and the deadline anchor clamp is loosened. Then a predetermined number of feet of wire rope is spooled onto the drawworks drum, thereby pulling fresh unused wire rope from the supply reel and into the system of sheaves. The place where the spent wire rope is to be cut is bound with tape and cut with either a manual or hydraulic cutting tool. This is done on the rig floor. The spent wire rope is removed from the drum and rig floor and the new wire rope end is threaded through the dogknot hole and clamped. Then the drum is rotated to spool several layers of wire rope, before the deadline anchor is re-clamped. Finally, the crown block hang-line is removed and drilling can resume.
It is therefore desirable to provide a brake, shear and cable management system mounted adjacent to the rotating drum in order manage, retain and sever a spent portion of cable upon the drum.
It is further desirable to provide a brake, shear and wire rope (cable) management system mounted to a drawworks housing (or rig floor) to safely and quickly move the wire rope through the crown and traveling block sheave system, clamp and cut the wire rope and control the wire rope movement and pull tension on the wire rope when spooling the drum.
It is yet further desirable to provide a brake, shear and cable management system having a cable management assembly, a cable brake assembly and a cable cutting assembly for maintenance and operation in a secure and more safe manner.
It is still further desirable to provide a brake, shear and wire rope (cable) management system that incorporates a remote wired or wireless control system that can allow the operator to be stationed in front of the drawworks drum, thereby reducing the risk of injury to rig floor personnel.
Other advantages and features of the invention will be apparent from the following description and from the claims.